1. Technical Field
The present invention relates to an inductor, and more particularly, to a multilayer inductor forming a coil part by multilayering a plurality of body sheets on which internal electrode patterns are printed.
2. Description of the Related Art
A multilayer inductor mainly used for a power supply circuit such as a DC-DC converter within portable devices has been developed to be small and implement high current, low DC resistance, or the like. Recently, as a demand for a high-frequency and small DC-DC converter is increased, a use of a multilayer inductor instead of the existing wound coil has been increased.
The multilayer inductor is configured of a laminate in which a magnetic part multilayered in a plurality of layers and a non-magnetic layer inserted into the magnetic part are complex and has a structure in which an internal coil of a conductive metal is formed in the magnetic part or the non-magnetic part and a punching hole is formed in each layer to connect with the plurality of layers.
As the magnetic body used for the multilayer inductor, ferrite including Ni, Zn, Cu, or the like, may be generally used and as the non-magnetic body, ferrite including Zn and Cu, Zr, or glass including TiO3, SiO2, Al2O3, or the like, may be generally used.
As such, the multilayer inductor causes degradation in inductance (degradation in DC biased characteristics) due to magnetic saturation of the magnetic body according to the increase in current. To solve the above problem, a method for increasing the DC biased characteristics by inserting the non-magnetic body in the same horizontal direction as a direction in which the magnetic body is multilayered has been used.
However, the non-magnetic body may be diffused to the magnetic body and thus, a loss coefficient of a material may be increased. Further, it is impossible to make a thickness of the non-magnetic body thin due to the diffusion to the magnetic body.
In addition, to solve the diffusion problem, a dielectric material may be inserted into the inductor, but coupling strength is reduced due to non-sintering and thus, breaking strength of the inductor may be reduced.